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Rapid solidification of metallic particulatesIn order to maximize the heat transfer coefficient the most important variable in rapid solidification is the powder particle size. The finer the particle size, the higher the solidification rate. Efforts to decrease the particle size diameter offer the greatest payoff in attained quench rate. The velocity of the liquid droplet in the atmosphere is the second most important variable. Unfortunately the choices of gas atmospheres are sharply limited both because of conductivity and cost. Nitrogen and argon stand out as the preferred gases, nitrogen where reactions are unimportant and argon where reaction with nitrogen may be important. In gas atomization, helium offers up to an order of magnitude increase in solidification rate over argon and nitrogen. By contrast, atomization in vacuum drops the quench rate several orders of magnitude.
Document ID
19820018557
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Grant, N. J. (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
September 4, 2013
Publication Date
January 1, 1982
Subject Category
Metallic Materials
Report/Patent Number
NASA-CR-169070
NAS 1.26:169070
Accession Number
82N26433
Funding Number(s)
CONTRACT_GRANT: NSG-7645
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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